The technology called “Mobile Inverse Mux” (see, for example, the document T. Nakata et al., “Efficient bundling of heterogeneous radio resources for broadband Internet access from moving vehicles,” in proceedings of Global Mobile Congress 2004, Oct. 11-13, 2004, Shanghai, China, and JP-A No. 2005-210671 (Paragraph 0312, FIG. 12)) is drawing attention as a technology for accessing the Internet from a moving vehicle such as a train traveling at a high speed in the range from 100 to 300 km per hour, a bus, or the like. This technology serves to achieve a wider band and increase the stability of communications by combining a plurality of communication modules such as of wireless LAN (Local Area Network) and cellular phone. In particular, for bundling a plurality of unstable communication routes for a wider band, it is necessary to monitor band fluctuations of the routes in order to effectively utilize the bands of the respective routes.
One process of measuring the band of a route between two nodes is known as a packet dispersion process for simultaneously transmitting a plurality of packets called a packet pair or a packet train from a transmission side, measuring a reception interval of the packets on a reception side, and estimating a band from the result of the measurement (see, for example, the document C. Dovrolis, P. Ramanathan and D. Moore, “What do packet dispersion techniques measure?,” proceedings of IEEE INFOCOM 2001, pp 905-914 (2001)). According to this process, the band of a link which causes a bottleneck to be created on the entire route is measured. Consequently, if the route includes a single wireless link, then the process can serve as a method for measuring the band of the wireless link.
A situation will be considered wherein nodes that communicate with each other are in a mobile environment and are connected to each other by a plurality of wireless links. In such a situation, it is necessary that any route between the nodes go through plural wireless links such as two wireless links. The total band of the entire route changes depending on the combination of wireless links through which packets are transmitted. Therefore, it is desirable to determine a combination of wireless links which can utilize the band most effectively after measuring the bands of all bottleneck candidates. According to the measurement of the bands of routes based on the related art of the present invention, however, it has been impossible to identify a bottleneck link in two wireless (narrowband) zones.
If there are a plurality of bottleneck candidate links such as wireless links in routes, then only low rate bands thereof are measured. As bottleneck links cannot be identified, there has been a problem in that it cannot be specified which links the measured values correspond to. Moreover, there is another problem in that the bands of links which do not serve as bottlenecks cannot be measured.